To clarify, PDAnet allows you to connect a laptop to the internet through your phone. I do not believe it can handle more than one connection at a time, and you need to be jailbroken to install PDAnet.
Actually I did mean router. A wireless router. No, not the PDAnet, I'm familiar with that. I mean...is there any way of using your iPhone as a wireless router, meaning that your iPhone would run some sort of dhcp server and dish out ips. The laptops with wireless could pick up from it and use the internet. PDA net allows you to use bluetooth, but not actual 802.11.